| 1. |
- Lona-Durazo, Frida, et al.
(författare)
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Meta-analysis of GWA studies provides new insights on the genetic architecture of skin pigmentation in recently admixed populations
- 2019
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Ingår i: BMC Genetics. - : BMC. - 1471-2156. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- Background: Association studies in recently admixed populations are extremely useful to identify the genetic architecture of pigmentation, due to their high genotypic and phenotypic variation. However, to date only four Genome-Wide Association Studies (GWAS) have been carried out in these populations.Results: We present a GWAS of skin pigmentation in an admixed sample from Cuba (N=762). Additionally, we conducted a meta-analysis including the Cuban sample, and admixed samples from Cape Verde, Puerto Rico and African-Americans from San Francisco. This meta-analysis is one of the largest efforts so far to characterize the genetic basis of skin pigmentation in admixed populations (N=2,104). We identified five genome-wide significant regions in the meta-analysis, and explored if the markers observed in these regions are associated with the expression of relevant pigmentary genes in human melanocyte cultures. In three of the regions identified in the meta-analysis (SLC24A5, SLC45A2, and GRM5/TYR), the association seems to be driven by non-synonymous variants (rs1426654, rs16891982, and rs1042602, respectively). The rs16891982 polymorphism is strongly associated with the expression of the SLC45A2 gene. In the GRM5/TYR region, in addition to the rs1042602 non-synonymous SNP located on the TYR gene, variants located in the nearby GRM5 gene have an independent effect on pigmentation, possibly through regulation of gene expression of the TYR gene. We also replicated an association recently described near the MFSD12 gene on chromosome 19 (lead variant rs112332856). Additionally, our analyses support the presence of multiple signals in the OCA2/HERC2/APBA2 region on chromosome 15. A clear causal candidate is the HERC2 intronic variant rs12913832, which has a profound influence on OCA2 expression. This variant has pleiotropic effects on eye, hair, and skin pigmentation. However, conditional and haplotype-based analyses indicate the presence of other variants with independent effects on melanin levels in OCA2 and APBA2. Finally, a follow-up of genome-wide signals identified in a recent GWAS for tanning response indicates that there is a substantial overlap in the genetic factors influencing skin pigmentation and tanning response.Conclusions: Our meta-analysis of skin pigmentation GWAS in recently admixed populations provides new insights about the genetic architecture of this complex trait.
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| 2. |
- Zhang, Tongwu, et al.
(författare)
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Cell-type-specific eQTL of primary melanocytes facilitates identification of melanoma susceptibility genes
- 2018
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Ingår i: Genome Research. - : Cold Spring Harbor Laboratory. - 1088-9051 .- 1549-5469. ; 28:11, s. 1621-1635
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Tidskriftsartikel (refereegranskat)abstract
- Most expression quantitative trait locus (eQTL) studies to date have been performed in heterogeneous tissues as opposed to specific cell types. To better understand the cell-type-specific regulatory landscape of human melanocytes, which give rise to melanoma but account for <5% of typical human skin biopsies, we performed an eQTL analysis in primary melanocyte cultures from 106 newborn males. We identified 597,335 cis-eQTL SNPs prior to linkage disequilibrium (LD) pruning and 4997 eGenes (FDR < 0.05). Melanocyte eQTLs differed considerably from those identified in the 44 GTEx tissue types, including skin. Over a third of melanocyte eGenes, including key genes in melanin synthesis pathways, were unique to melanocytes compared to those of GTEx skin tissues or TCGA melanomas. The melanocyte data set also identified trans-eQTLs, including those connecting a pigmentation-associated functional SNP with four genes, likely through cis-regulation of IRF4. Melanocyte eQTLs are enriched in cis-regulatory signatures found in melanocytes as well as in melanoma-associated variants identified through genome-wide association studies. Melanocyte eQTLs also colocalized with melanoma GWAS variants in five known loci. Finally, a transcriptome-wide association study using melanocyte eQTLs uncovered four novel susceptibility loci, where imputed expression levels of five genes (ZFP90, HEBP1, MSC, CBWD1, and RP11-383H13.1) were associated with melanoma at genome-wide significant P-values. Our data highlight the utility of lineage-specific eQTL resources for annotating GWAS findings, and present a robust database for genomic research of melanoma risk and melanocyte biology.
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| 3. |
- Al-Dajani, Haya, et al.
(författare)
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A multi-voiced account of family entrepreneuring research : expanding the agenda of family entrepreneurship
- 2023
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Ingår i: International Journal of Entrepreneurial Behaviour & Research. - : Emerald Group Publishing Limited. - 1355-2554 .- 1758-6534.
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Tidskriftsartikel (refereegranskat)abstract
- PurposeThis conceptual, multi-voiced paper aims to collectively explore and theorize family entrepreneuring, which is a research stream dedicated to investigating the emergence and becoming of entrepreneurial phenomena in business families and family firms.Design/methodology/approachBecause of the novelty of this research stream, the authors asked 20 scholars in entrepreneurship and family business to reflect on topics, methods and issues that should be addressed to move this field forward.FindingsAuthors highlight key challenges and point to new research directions for understanding family entrepreneuring in relation to issues such as agency, processualism and context.Originality/valueThis study offers a compilation of multiple perspectives and leverage recent developments in the fields of entrepreneurship and family business to advance research on family entrepreneuring.
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| 4. |
- Gunnarsson, Ulrika
(författare)
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Genetic Studies of Pigmentation in Chicken
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Domestic animals have been selected by humans for thousands of years, which have drastically altered their genetic constitution and phenotypes. In this thesis, several of the most important genes causing pigmentation differences between the wild red junglefowl (Gallus gallus) and domestic chickens have been identified. Pigmentation phenotypes are easily scored, and the genes underlying these phenotypes are valuable models to study gene function and gene interaction. Dominant white colour is widespread among domestic chickens. The Dominant white allele specifically inhibits the expression of black (eumelanin) pigment and we identified several insertion/deletion mutations in the PMEL17 gene causing the different phenotypes controlled by this locus. The Silver allele on the other hand inhibits the expression of red (pheomelanin) colour and is a genetic variant of the SLC45A2 gene. Silver is the first pheomelanin-specific mutation(s) reported for this gene. An 8 kb deletion, including a conserved enhancer element, 14 kb upstream of the transcription factor SOX10 is causing the Dark brown phenotype. This phenotype restricts the expression of eumelanin and enhances red pheomelanin in specific parts of the plumage. These three gene identifications have extended the knowledge about genes affecting melanocyte function. Carotenoid-based pigmentation is of utmost importance in birds and other animals. The yellow skin allele in chicken allows deposition of carotenoids in skin and explains why most domestic chickens have yellow legs. We demonstrated that the yellow skin phenotype is caused by a tissue specific regulatory mutation in the gene for the enzyme beta-caroten dioxygenase 2 (BCDO2). This was the first identification of a specific gene underlying carotenoid-based pigmentation. Interestingly, the yellow skin haplotype was shown to originate from the grey junglefowl (Gallus sonneratii) and not the red junglefowl as expected, thus presenting the first conclusive evidence for a hybrid origin of the domestic chicken.
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| 5. |
- Kübler, André, et al.
(författare)
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Mycobacterium tuberculosis dysregulates MMP/TIMP balance to drive rapid cavitation and unrestrained bacterial proliferation.
- 2015
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Ingår i: Journal of Pathology. - : Wiley. - 0022-3417 .- 1096-9896. ; 235:3, s. 431-444
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Tidskriftsartikel (refereegranskat)abstract
- Active tuberculosis (TB) often presents with advanced pulmonary disease, including irreversible lung damage and cavities. Cavitary pathology contributes to antibiotic failure, transmission, morbidity and mortality. Matrix metalloproteinases (MMPs), in particular MMP-1 are implicated in TB pathogenesis. We explored the mechanisms relating MMP/TIMP imbalance to cavity formation in a modified rabbit model of cavitary TB. Our model results in consistent progression of consolidation to human-like cavities (100% by day 28) with resultant bacillary burdens (>10(7) CFU/g) far greater than those found in matched granulomatous tissue (10(5) CFU/g). Using a novel, breath-hold computerized tomography scanning and image analysis protocol. We show that cavities develop rapidly from areas of densely consolidated tissue. Radiological change correlated with a decrease in functional lung tissue as estimated by changes in lung density during controlled pulmonary expansion (R(2) =0.6356, p < 0.0001). We demonstrated that the expression of interstitial collagenase (MMP-1) is specifically greater in cavitary compared to granulomatous lesions (p < 0.01), and that TIMP-3 significantly decreases at the cavity surface. Our findings demonstrate that an MMP-1/TIMP imbalance, is associated with the progression of consolidated regions to cavities containing very high bacterial burdens. Our model provided mechanistic insight, correlating with human disease at the pathological, microbiological and molecular levels,. It also provides a strategy to investigate therapeutics in the context of complex TB pathology. We used these findings to predict a MMP/TIMP balance in active TB; and confirmed this in human plasma, revealing the potential of MMP/TIMP levels as key components of a diagnostic matrix aimed at distinguishing active from latent TB (PPV=92.9%; 95%CI 66.1-99.8%, NPV=85.6%; 95%CI 77.0-91.9%).
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